MECHANICAL-PROPERTIES OF HETEROCYCLIC POLYMER NETWORKS

Heterocyclic networks prepared by copolymerization of oligomeric epoxy rubber (ER) with different amounts of hexamethylene diisocyanate (HMD I) were characterized by room-temperature 'static Young's and bulk mod uli, as well as by measurements of dynamic Young's modulus and linear thermal expansivity in the temperature interval 293-503 K. It was conc luded that the major factor affecting thermoelastic properties of thes e networks is the relative content of three-arm, six-membered isocyano ureate rings which determine the apparent overall network density, and of two-arm, five-membered oxazolidone rings which act as a sort of '' internal diluent''.